This invention relates mainly to an emergency PTO driving unit of a vehicle for industrial machinery.
Generally, this kind of driving unit is used for actuating the vehicle power steering, etc., in an emergency such as engine trouble etc., and rotation of a wheel, or a battery, is utilized as the driving units power source. Namely, in a case such as when a vehicle is towed by an other vehicle due to engine trouble, etc., this driving unit allows the towed vehicle's power steering to function normally.
An emergency PTO pump has conventionally been equipped as the PTO driving unit, and the following installing methods have been employed.
The first method is that in which the emergency PTO pump is normally equipped on a vehicle and the pump is always actuated by utilizing rotation of a wheel even in case of no emergency. However, in such a construction, power loss will be generated during normal running and troubles could occur in the PTO pump before an emergency actually arises.
The second method is that in which the PTO pump is installed when an emergency of a vehicle arises. In this construction, however, a great deal of labour is required in installing the pump. Further, in a case such as when a vehicle breaks down on a down-slope, it would continue running with its steering wheel inoperable.
The third method is that in which a vehicle is equipped with a motor driven by a battery mounted thereon and the PTO pump is actuated by that motor. In this construction, however, the pump can be used for no more than the service life of the battery.
An object of this invention is to overcome the disadvantages of the above conventional embodiments. In order to accomplish this object, in this invention, an emergency PTO driving unit includes an emergency PTO pump which is normally equipped on a vehicle for industrial machinery, said emergency PTO pump is interconnected through a clutch unit to an axle to utilize rotation of a wheel as a power source for driving the pump, and said clutch unit is so composed that the clutch is brought into a "disengaged" state by means of a hydraulic pressure supplied from a proper hydraulic pump driven by an engine when the engine is running, and the clutch is brought into an "engaged" state by means of a spring means when the engine is stopped.